Frugal fashionistas overloaded her server in December, looking to stay in style after they had lost their paychecks.

"When people started getting laid off, all of a sudden we went from 4,000 to 7,000 users," De Frias said. "It never stopped, and now we add another 800 or 900 a month."

The spike on De Frias' site matches a major upswing in online bartering sites as shoppers look for freebies to survive the economy. In the Bay Area, home to Craigslist and Freecycle, bartering is a flourishing underground economy. More than 30,000 people in the Bay Area are now exchanging books, CDs and video games on Swaptree.com. This year Craigslist has reported a 100 percent increase in traffic on its bartering boards.

Clothing swaps have gone from private parties among girlfriends to big warehouse events with DJs, open bars and tickets. The queen of swap, Suzanne Agasi, was among the first to organize large-scale clothing swaps when she started Clothingswaps.com in the Bay Area 15 years ago. She's since held more than 170 events in more than a dozen cities.

In the beginning, most of the women who showed up to her swaps were students or nonprofit workers with tight budgets. Now women with "really good jobs and expensive wardrobes" are coming out of necessity, she said.

For her "fashion stimulus" price of $20, women can leave her swaps with a bagful of designer clothing.

"If you gotta tighten your belt, let it be somebody else's," she said.

More than 1.5 million items and services are listed for trade at U-Exchange.com, the granddaddy of all swap sites. Based in Toronto, the site facilitates barters of everything from carpentry to cars to vacation homes. It saw a 70 percent increase in new members in May over last year to more than 14,000. Page views are up 123 percent.

Swapper Kristin Flynn of Mill Valley hasn't paid for a book or video for her three young sons in two years.

When her children outgrow their Thomas the Train or Wiggles phases, she lists the books and videos online, and Swaptree instantly matches her with people around the country who want to trade for the items on her wish list.

All she pays is postage - after printing out a prepaid label from Swaptree.

"This is a huge way to save money," said Flynn, who trades something every two weeks. "I don't know how the site makes money, but I don't really care as long as they stay in business."

Mark Hexamer, co-founder of Swaptree, said the site isn't making a profit yet from its online advertising, but expects to soon. The Boston site has doubled its listings every three months since launching in July 2007.

"Free and green are good buzzwords right now," Hexamer said. "The greenest product of all is no product."

The Coastside Mothers Club swap that started three years ago as a small gathering between moms in Half Moon Bay now draws more than 100 people looking for baby clothes, maternity wear, strollers and toys.

"The economy hit us big time," organizer Carolyn Mendez said. "Now that everyone is watching their money, it just keeps getting bigger."

With the database power of the Internet to link people who have what someone else wants, swapping is likely to stay, even after the economy bounces back, said John C. Moore, founder of U-Exchange.com.

"We started four years ago when the economy was good and built a base of people getting what they wanted without money, and then we were there for them when things took a downturn," Moore said.

For clothing designer Anayma de Frias, the Internet has ushered in a new era of sharing that will turn high-priced fashion on its head.

"We're seeing on our forums that people are getting more involved with people in their own ZIP codes, trading with them to avoid postage, or even forming their own swap meets," she said.

"I can't imagine once people start getting jobs again they are going to throw money where they learned to get things for free."